Mass spectrometry methods for studying protein-metal binding

• Main Author: Dong, Jia
• Language: ENG
• Published: ScholarWorks@UMass Amherst 2014
• Subjects: Chemistry|Analytical chemistry
• Online Access: https://scholarworks.umass.edu/dissertations/AAI3615409

This dissertation focuses on the mass spectrometric based methods for studying protein-metal binding. Identifying metal-protein interaction is a key step in understanding metal-binding protein structure and function. A phenomenon associated with gas phase dissociation behavior of metal-peptide complexes has been investigated. A positive correlation was found between the number of strong coordination groups in the peptide sequence and the degree of c and z ion formation after electron transfer dissociation of the peptide-metal complexes. Establishing thermochemical cycle enables a theoretical understanding of the process. A new mass spectrometric method has been developed to identify Zn-bound His residues in Zn-metalloproteins relies on variations in the hydrogen deuterium exchange of the C2 hydrogen of His side chains. We show that this approach can be used to study the Zn-bound His residue in human &beta-2-microglobulin; (&beta2m;), a monomeric protein that has been shown to aggregate into amyloid fibrils in dialysis patients leading to dialysis-related amyloidosis. The different effect of three divalent transition metals including Cu(II), Ni(II) and Zn(II) on &beta2m; oligomerization and fibril formation under physiological conditions is described. We found that Cu(II) can induced &beta2m; oligomerization and amyloidosis. In contrast, no oligomeric species can be formed with Ni(II), and only oligomers can be formed with Zn(II). A combination of metal catalyzed oxidation (MCO)-MS, hydrogen deuterium exchange (HDX)-MS and other spectroscopic techniques is utilized to obtain insights into the mechanism of Cu(II)-induced &beta2m; amyloidosis. We elucidate the different ways that these metals bind &beta2m;, thereby identifying key features of the &beta2m-Cu;(II) interaction that are essential for enabling this protein to form amyloid fibrils.